It is proposed to study some aspects of the structure of connective tissue proteoglycans. Initially only cartilage will be used as a source, as the structure and function of its proteoglycans are already partially understood. Particular emphasis will be given to the separate isolation of the link proteins which interact with and are believed to stabilize proteoglycan aggregates. The amino acid and carbohydrate composition of the link protein will be determined, and methods for their specific cleavage to yield fragments which are amenable to peptide sequencing will be investigated. Efforts will be made to relate sequence information obtained to the hyaluronate and proteoglycan binding properties of the link proteins. At present it is not known whether proteoglycans in connective tissues other than cartilage for aggregate structures or whether the link proteins are even present. To permit identification and quantitation of link proteins, especially in cardiovascular tissues, suitable immunological procedures will be developed. The proteoglycans from an elastic tissue, rabbit ear cartilage, will be isolated in order to investigate proteoglycan-elastin interactions. Such interactions of proteoglycans may be important in the normal functioning of the artery wall.